An air intake of an internal combustion engine may include an air filter so that debris may not be drawn to an engine where the debris could cause engine degradation. The air filter may be position in an engine air intake upstream of a throttle so air entering the engine is filtered as soon as it enters the engine air intake. One way to estimate whether or not an air filter is degraded is to determine an air pressure drop across the air filter at a steady air flow amount through the air filter. However, a driver of a vehicle may often change the engine torque demand to meet driving conditions. An increasing driver demand torque may increase air flow through the air filter while a decreasing driver demand torque may decrease air flow through the air filter. Such torque and air flow changes may occur frequently so that establishing constant air flow through the air filter may be difficult and infrequent. As a result, reliable estimates of air filter performance may be delayed while debris continues to accumulate in the air filter. As a result, engine performance may degrade before conditions are established where the air filter may be reliably diagnosed.
The inventors herein have recognized the above-mentioned limitations and have developed an engine air filter diagnostic method, comprising: indicating via a controller, engine air filter degradation in response to a mean of a pressure change across an engine air filter, the pressure change across the engine air filter based on data observed via the controller during transient air flow conditions through the engine air filter.
By judging the presence or absence of engine air filter degradation in response to a mean of a pressure change across the engine air filter, it may be possible to provide the technical result of evaluating an engine air filter during transient air flow conditions through the engine air filter. In particular, a mean and a standard deviation of a pressure change across an engine air filter may be a basis for determining and indicating engine air filter degradation. The mean and standard deviation may be determined based on data taken during steady state or transient air flow through the air filter. Consequently, air filter degradation may be evaluated over a wider range of engine operating conditions so that a driver of a vehicle may be timely notified of air filter degradation.
The present description may provide several advantages. In particular, the approach may provide more timely notification of engine air filter degradation. In addition, the approach may provide an indication that engine power is reduced. Further, the approach may provide an estimate of a remaining useful life cycle so that a driver may know when an air filter is approaching a degraded state.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.